Centrifugal pump? Twin lobe pump? Piston? Peristaltic pump?
Aparently very cheap ones. I hand picked an Einheim german made pump for my system because they are long lasting high performance. I use 1/2" tubing and this pump pushes some serious water through that thick tubing no problem.
On my old system I had a Thermaltek Aquarius II unit that had a tiny pump. It worked ok for a Socket A Athlon but not enough for newer chip. It had a tiny little pump/reservoir.