A damper is provided for a well system. The well system utilizes a pressure pulse generator in the wellbore to generate a pressure pulse through fluid, such as treatment fluid, in the wellbore. The damper is received in the wellbore to damp transmission of the pressure pulse through the fluid while also allowing fluid to flow through the wellbore between a terranean surface and a location adjacent the pressure pulse generator. In certain instances, the damper allows flow of fluid past the damper while damping transmission of the pressure pulse through the fluid.