Wiped cam/lifter?
John, I can see metal particles getting into the oil pump (the pick up screen is pretty course) but the oil filter should stop everything else. Anything small enough to get through the filter will pass through the bearings.
It was pretty standard back in my younger days working in a garage to swap the cam lifters and flush the pan real well then do a couple of oil changes a few hundred miles apart. Never had a premature bearing failure.