Cam bearings

In looking at the bearing surface of the cam's and the caps on my 93 2.0 I noticed things aren't looking too well, both look scored, not terribly but bad enough that I want to repair the damage. The problem is that there do not seem to be any replacable bearings in this cam bearing setup, nothing in the head or the caps.
So what, if the cam bearings go on these things you have to replace the head? or do machine shops machine in a set of bearings on a rebuild?
Kind of a crappy design if you ask me.
Since I just bought the car I have to wonder as well why the bearings are scored, are they prone to do this, since only # 1 and # 2 bearings on the back cam are scored I'm wondering if there is a problem with lack of oil or overheating to this area or what, seems if it was caused by foriegn material in the oil all the bearings would be affected.
All car makes have their good and bad points but so far nothing about this mazda/ford designed automobile has impressed me, I hope this changes once I get it back together and running.