When I went through this exercise I took my entire motor to the bear specialist place. At first they were very confident that they would have something on the shelf or could order something in overnight. When they pulled out the bearing and measured it, I was told it was not a standard size and referred me back to the manufacture of the pump.
Very frustrating. For the life of me I can't understand why someone when engineering this wouldn't use a standard off the shelf part. I'm sure there's an answer here somewhere and a way for us to rebuild these but if we are able to find a source we'll probably have to do a volume purchase to afford the rebuild parts.