Hi Mike,
What you are describing is normal as the others have said. There is steel on steel and it will wear "some". More so in the beginning until the contact patch becomes larger the then the wear slows down.
I will highlight as was said by the other poster, you need to mark the left and right WD bar and keep them on the same side all the time. The WD bars and the new DC's are not machined. They are not the same exact length/diameter. You adjust the cam arm to be dead centered in the V of the WD bar. This compensates for the differences and creates a matched set. A wear pattern is created between the cam and the WD bar that is this matched set. If you do not put that same WD bar back on the same side, the wear pattern starts all over again.
To show you this, see pics below. Those pictures was taken after 25,000 miles with a TW of 1,200# on my prior camper. These are my original cams bought in 2003.
I have since moved those same cams to my current trailer and have well over 30,000 miles on them with a 1,600# TW and 1,700# bars and the wear is not a lot more. Since I have this heavy TW, or even on the 1,200# camper, I did use Vase-O-line and it helps on the noise and the wear. If you are at or over 1,000# TW, a very light vase-o-line coat will help. DO not use grease, it cuts too much friction.
After I hit between 75,000 to 100,000 miles I may flip these cams over and start wearing again.
I know you are looking at a Blue Ox, do not know what issue you are trying to fix WD wise or sway control wise, but the Blue Ox will not fix what the Reese hitch and DC cannot correct as far as WD and anti sway. A setup or something else is the issue.
Hope this helps
Right side
left side
The 1,200# WD bars
