A high temperature centrifugal pump includes non-linear fluid flow paths between the pump housing and seal housing to reduce fluid flow therebetween. In another aspect, the invention provides a drive shaft of variable diameter to compensate for different amounts of thermal expansion to maintain a more consistent gap profile between the drive shaft and thermal insulators or other components positioned around the drive shaft. In yet another aspect, a tube heat exchanger may be placed in fluid communication with the seal housing to re-circulate and cool the fluid therethrough.