Dear Noreen,
This looks like the underside of the leaf with pear rust, a fungal disease.  Do the tops of the leaves have a rust colored circle?
Taking them off is an excellent idea and putting them in the trash.
There is a sulfur spray you can use to stop or limit the growth of the fungus.  Look for Safer fungicide.  It is ready to use, mixed, please follow the instructions to the letter.
Sulfur can burn, so make sure you are wearing long sleeved clothing, mask, gloves and safety glasses.
Do not over spray, sulfur can harm the tree if used excessively and spray when there is no wind and the temperatures are between 40 and 80 degrees.  It should be dry and stay dry (no rain) for 24 hours.
Pick up any leaves that fall to the ground as well.  In the fall when all the leaves fall, make sure to clean all of them up and put in the trash.
Here is some additional information:  https://extension.okstate.edu/fact-sheets/pear-rust.html
And additional information for the PNW Oregon State:  

Bartlett pear is not as susceptible but will show symptoms on some fruit.

Jay W. Pscheidt, 2015.

Close up of orangish cup-shaped pustules (aecia) on Pyrus calleryana (Bradford pear).

Luisa Santamaria, 2012.

Pear rust can also occur on the flower petals as well as leaves and fruit.

Jay W. Pscheidt, 2012

Note the reddish, yellow lesions on these young, misshapen fruit.

Photo by Jay W. Pscheidt, 1993.

This is a scanning electron micrograph of aecia and aeciaspores (150x).

Photo by Al Soeldner, 1999.

"Numerous rust pustules (uredia) can be seen on these flowering pear leaves (Pyrus calleryana).Photo by Melodie Putnam.

See:

Cedar, Incense - Broom Rust

Pear (Pyrus spp.) - Trellis Rust (European Pear Rust)

Cause Gymnosporangium libocedri, a fungus. The rust fungi in this genus alternate between a conifer and roseacous host. Similar spore stages on pear are produced on apple, crabapple, hawthorn, mountain ash, quince and serviceberry (Amelanchier). The alternate host is the incense cedar (Calocedrus decurrens). The disease has been reported commonly from the Willamette Valley of Oregon, but outbreaks are economically significant to orchardists only every few years. Oriental and European cultivars are susceptible. (Note that G. asiaticum occurs on Asian pears.) 'Winter Nelis' is severely affected while under the same conditions 'Bartlett' is less affected. Some years 'Bartlett' can be severely affected but other pears show even greater symptoms under the same conditions.

Symptoms Pear fruit are malformed while young and drop from the tree. Bright-yellowish to orangish spots with numerous cup-shape pustules (aecia) develop over the fruit surface. Spots fade and darken as the fruit matures or falls off the tree. Green shoots and leaves also are attacked but not as frequently. Symptoms are most obvious after flowering but before July.

The disease on Incense cedar is called broom rust because it causes a witches' broom. Telia develop only on the leaves and are not very noticeable until during spring rains when they look like orange jelly. Trees with many infections decline and may die.

Cultural control Remove alternate hosts around the orchard."

Since this is a brand new tree, you might return it.  If you have an Incense Cedar in your area, you can also spray it.

Thank you for contacting us if you have further questions, send us an email.