You know, i just took apart an engine last week that was toasted.
When I went to pull the cam, it would not come out. Finally it did...but one of the cam bearings cam with it. Finally got the entire cam out of the block, and the bearing fell off inside, and once I retrieved it, it looked a lot like yours.
A few rod bearings looked the same too. In this motors case, the reason for failure was either NOT changing their oil like they should or using very crappy oil if they did (massive build up and deposits through out the block) or they ran the oil low. My main guess would be a leaky LIM or Head gasket wiped this motor out if I had to put money on it because of what the cylinders looked like. So in this case...water/coolant in the oil did the damage for mine.
~F~