Abstract Dredge pumps are prone to irreparable damage during offshore constructions: the flow passage components are rapidly worn out, and pump shafts often break. It seriously affects the construction efficiency and progress. For the case of high concentration conveying of medium coarse sand, the flow in a dredge pump was numerically studied to analyze the flow force on the impeller and the trajectories of sand particles in the impeller. A discrete phase model was introduced to predict the wear on the impeller, and the life of the pump shaft was predicted using S-N curves and the Rain-flow counting method. A new blade profile and an endwall profile were proposed to use to reduce the wear on the impeller and the structure of the shaft head were optimized to reduce the stress concentration coefficient. The numerical results showed that these measures can significantly improve the service life of the pump.