Looks like serious fretting/seizing to me. There are no signs of wear in the region around the oil holes, so I would think it had been caused by lack of oil pressure (and/or the crankpin is out of round), resulting in mixed/solid friction in the lower part of the bearing when exposed to combustion forces. If the premature wear had been caused by abrasive particles, I would expect signs of it around the whole bearing surface, so also around the oil holes and on the top side, but as far as I could see on the pic, everything looks pretty smooth there.
I can only suggest a theory here, however I dare to say that this is not what a timing side bush looks like when exposed to normal wear after considerable mileage, this damage looks very much like lack of lubrication to me.
I think it would definitely be advisable to check the whole lubrication system, incl. the pump(s), all valves (return, pressure relief) and passage ways.
You didn't have one of those anti-wet-sumping things fitted?
Open for discussion, looking forward to hear other's opinions. I think the evaluation of damage is one of the most interesting fields in engineering, although this probably won't be any consolation for the owner....
HTH, Markus