That’s good news you are the exception however I was not as lucky well neither were my other colleagues here northern states. We all had water pump replacement around 700-1000 hours.Have to disagree with the water pump failures on Kubota, I have about 8 here ranging from 650-4000+hrs and all on the original WP, at least 4 of them are over 3000hrs. The newest one is 2010 and the oldest is sometime in the 80's.
As for the fan, guessing either improper material selection or as stated just a bad mix.
As far as fan material they are molded out of nylon 6/6 common material. However nylon does not like adverse dry no humidity conditions. It will stress crack leading to failure. Need to ask the question we’re there any concentrated white spots where the fan cracked. This would be defined stress point. Thanks for sharing your opinion and longevity of your water pump. I was also told to inspect water pump yearly which meant to relieve pressure from belt. Then grab the fan and see if it wobble or move side to side. Dealer stated clearly once the water pump goes the engine temp can rise quickly under load and risk taking a head gasket if not caught quickly. I can only speak for my first hand experience, I caught my pump failing.