Bill
Eric here with an update on my project after cleaning all the parts up from my front brake job I noticed very light rust shadowing on my onboard wheel bearing rollers and decided to replace both inner bearings and races .
I imagine that's what's happened to yours overtime the rust breaks through the hardening and metal transfer begins rendering the bearings useless in a short period of time.
Hope this helps explain how even relatively new bearings can go bad.
If you get pics of the dead bearings I may be able to tell you what caused your failure.
Good luck
Eric