Copper failing under the house
when conduit or plumbing is  covered in concrete it must be insulated from the cements high alkalinity, otherwise the metal will corrode and eventually fail. I don't believe the circulating pump has any detrimental effect on your copper pipe. Although it should be on a thermostat so it only works when needed. What I've noticed alot more in recent years is the quality of copper pipe (most imported from overseas) has become much lower. This and a high pH level could be why the copper is failing. If you are going to replace any damaged pipes it would be wise to re-route the pipes in the concrete to be safe. PEX when installed properly is the better alternative than copper.