Rear ABS wheel bearing problem - Advice please?

I can't understand how the ABS ring has got ground flat like that, if the wheel bearing had collapsed to the point the ABS ring had been ground flat I would have thought that the ABS sensor would have also been ground away, unless it fell the other way?

It seems to me that there must have been something else in the hub grinding the ABS cogs off the retaining wheel? It could have been a bit of the bearing? What is the inside of the hub like, any clues?

As the bearing collapses the castellated pickup ring would hit the top of the mount, the ABS sensor is recessed on the front facing side…

 

Worn away whilst fitted to the motor! Sorry I do not buy that one. The amount of damage would be horrendous and the "worn away" ring would be mangled as would be the casing. I suggest the ring was machined off before fitting.

Roger

Whilst I cannot solve the mystery of what has happened perhaps I can add in some background information

The early ABS retainers were a two part assembly. There was a bearing retainer ring and an ABS ring sweated onto the outside. The later ones, such as Dave has pictured, are a single part. The later part supercedes the early part and is a direct replacement. 
It almost looks like the original posted picture is an early one with a separate ring where the ring has either being machined or even replaced with some sort of sleeve.