The heat output by the pump is not trivial. It could well be pushing your heatload into the range pH described. (how are you measuring temps, btw? watercooling is known for tricking motherboard probes into reporting higher temps than they should.) If the pump is inside the res, ALL of its rated power is going into that loop as heat.
I'd also do a finger-test at various points on the loop to make sure it's insulated well enough. If it feels cool to the touch, it probably could use another layer of insulation.
I don't want to discourage you from using TEC chillers (one of 'em is my current pet project!), but I will point out that there really isn't an advantage to using them over a compressor. If you don't mind the noise, something with a decent compressor may very well outperform the tec chiller.
If you want to dig deeper, you could work out the energy balance for the loop to see how much heat it's gotta be absorbing from the pump + surroundings, and subtract the number of watts the pump draws in current to get a rough idea of how much heat's being added to the loop through the tubing walls and such.
If you're up for a project, my own
thread might be worth perusal. You could probably top my setup easily in terms of both efficiency and performance if you custom built your own chiller block.
edit: typos