Great idea Peachguy!! Yes you definitely do have to have two pears as they don't self pollinate.
The apple tree that flowered, but did not bear fruit, may have been too young, but it also may not have been fertilized either. It all depends on which way the wind is blowing, where the bees land that day.....
Often too, if your trees are blooming, and a frost hits, the fruit your trees bear will be less as the blossoms die.
I have had my trees be covered all over with blooms, and then only bear fruit on one side - the frost came in, but there was also a light breeze that kept it off one side. It looked very strange!! Sometimes we have no control, Mother Nature has her own plans!