Looks like one of the Gymnosporangium rusts that affects members of the Rosaceae family. Somewhere in the viciinty there is a host species, typically a juniper, that is providing the spores that infect the pear. Removal of the host is the recommended solution but spraying at appropriate timings can help.

Thank you, gardengal48!

You nailed it. I found related article from Virginia Tech:

https://www.ppws.vt.edu/extension/plant-disease-clinic/disease-advisory/201505-Gymnosporangium_Rusts.html

Preventative fungicide applications for rust diseases on Rosaceous plants are recommended and are best initiated at bud break. Repeated applications will be required while spores are being produced on the alternate gymnosperm host during the spring.

What fungicide is effective on this rust?

Anything that contains chlorothalonil (Daconil) or mancozeb as the active ingredient or a fixed copper spray.

Great!

That helps a lot! Thanks!

I will give it a try next spring to make sure the tree will have nice leaves and fruits.