To control the flow of the hot water, some Radiant Systems use one pump on each zone others use one main pump and a zone valve for each zone.
I might suggest if you only have a couple small zones the single pump with a zone valves would be a good choice, like the picture on the left.
But if you have a fair number of zones and the zones are large, then I would suggest an individual pump for each zone. In reality, the pump with flange is about the same price as a zone valve, and assures positive flow to each loop.
Also, it is imperative that any radiant loops in concrete use a mix valve to temper the water temperature. 110 degrees in the concrete is usually plenty.