A manually operable pump for dispensing creamy substances from a container on which the pump is mounted, and for preventing emergence or leakage of creamy substances along the outer surface of the pump stem when the pump is at rest and the container on which it is mounted is inclined to the upright position, with the pump at least partly immersed in the creamy substances. The pump comprises two separate seal regions provided between the pump main body and the piston and respectively the stem of the same pump.