I took my boots to the local cobbler. He looked over the "rubbed spot" on each boot. After talking a few minutes, he suggested sewing in a piece of pigskin leather to cover the worn holes and to cover the stitching near the heel. He also says that the hole rubbed is indicative to boots being a bit too big. I did not disagree on the sizing issue. My CBTs are sz 43 which is about a US 9.5. I generally wear a US 9. He then suggested to get a Superfeet insole that is thicker than the one I had in the boot. I was using the Blue Superfeet insoles. I switched to the Copper DMP which is a bit thicker insole to take up some of the boot slop and to make up that 1/2 size.
Overall, I am 90% satisfied. I had to break in the newly added pigskin...that took a couple weeks. But now the boots do seem to fit better and there is no more rubbing on the back...well, not as much rubbing. It seems that my right foot is slightly bigger than my left. It seems that is normal, according to the cobbler. Anyhooo...with thinner socks I do have some slight rubbing, but with my normal boot socks the rubbing is very minimal and the boots wear good once again.
Here are the results. 30$ for the pigskin and 40$ for a new set of Smartfeet insoles.