Hot water return systems are not part of "normal" residential plumbing. They are energy wasting, obnoxious high-end stuff that you expect to find in what they

Hot water return systems are not part of "normal" residential plumbing. They are energy wasting, obnoxious high-end stuff that you expect to find in what they call a "McMansion". The electric pumps they use last much less than the 10 to 20 years you mention. A plumber who considered himself a craftsman, say having given up a higher paying computer job to build nice plumbing systems, would not install one. But if he did, it would not cavitate. If you have observed shorter life in the joints near those pumps, it is because the pipe corrode faster there because they are always at a higher temperature, just as the hot water outlet on a water heater always corrodes before the cold water inlet.