I assume that the cooling system doesn't leak and holds the factory pressure. (Water boils at higher temps under pressure). Also that the water pump belt has been checked. This requires you to answer a few questions for yourself. When the engine is hot and running, does the cooling fan work? Your car has an electric fan behind the radiator. If it also has A/C, turn on the A/C and look at the fan to see if it's running. I would check the fuse and also the fan relay if it isn't.
Also, you don't say which engine you have, but the 3100 V6 is notorious for developing air pockets in the water jacket if the cooling system is opened (which you would have done when replacing the pump). This will keep the coolant from flowing through the radiator and will cause overheating. There is a small brass bleeder valve on top of the bypass tube that sticks out the top of the water pump housing on this engine - open it slightly by loosening the top "bolt" a couple turns with the engine running (don't remove it, and be careful of the moving belt!); if you don't get a little trickle of coolant out, there's air trapped in your cooling system. With the engine still running, leave the valve open and add coolant until a steady trickle does come out through the valve (not just a little foam). Then close the valve and add enough additional coolant to bring the bottle up to the full line. Work quickly, the engine will get hot fast with the pressure cap off. Good luck.