The invention relates to a pump for pumping contaminated liquid comprising solid matter, the pump comprising a hydraulic unit (2), a drive unit (3), and a sealing unit (4), the hydraulic unit having a pump chamber (5) and an impeller (8) that is suspended in a drive shaft (9), said impeller and said drive shaft forming a rotatable unit, the sealing unit comprising a seal housing cover (15) that delimits said pump chamber (5) and that forms a seat for a drive shaft sealing assembly (16), the seal housing cover (15) comprising a first gap-delimiting part (20) and the rotatable unit comprising a second gap-delimiting part (21), which jointly define an axially extending gap (22) situated in the pump chamber. The pump is characterized in that, in each arbitrary radially extending plane taken through said gap (22), the first gap-delimiting part (20) has a broken circular outer gap-delimiting surface (23) at the same time as the second gap-delimiting part (21) has a broken circular inner gap-delimiting surface (24).