Circulating Pump Hydronic

I seem to remember that the circulating pump should be on the return side of a radiant floor system loop, as it is cooler, and theoretically should make the pump last longer. How would you write it up, if at all?

I wouldn’t write it up without a better reason.

The temp differential is only around 20 degrees.

Your links subject was more important than my original concern. Somewhat humbling.
Thank you.