The experience on this site is mostly with pumping water at say 35+F, so I don't know how much feedback you will get. A couple things, though:
1. The pump needs to be designed to work under these conditions. The seals, plastic, etc. of a pump designed to move water is not going to stand up to temperatures of -140F.
2. The pump will always add some heat to the fluid. It could be a small amount of heat, but there will be some. You are doing work on the fluid but moving it around, so that means friction, which equals heat. There will also normally be some heat from the motor itself to the fluid. However, this may be minimized if the pump motor has its own liquid cooling.
You will need to see what is out there in terms of cryo pumps. Do you know the flowrate or other specs for this cooling system? How much energy do you need to remove?