Abstract: Key metallic structures in marine and hydraulic engineering are prone to damage when serving in abrasive environments for a long time, which may lead to structural safety risks in severe cases. However, systematic research on the wear resistance and wear mechanism of surfacing layers of underwater repair electrodes is still relatively insufficient. Two types of underwater repair electrodes were designed, and multi-layer and multi-pass underwater surfacing tests were conducted. The microstructure, microhardness, and wear resistance of the surfacing layers were obtained. The results indicate that the top and middle layers are mainly composed of lath martensite and columnar δ-ferrite, while the bottom layer, affected by the welding thermal cycle and the change in cooling rate, forms a microstructure dominated by tempered martensite. After the introduction of rare earth elements, the δ-ferrite is significantly refined and tends to be dispersed. The nucleation of lath martensite at the δ-ferrite grain boundaries increases and is more uniformly distributed, resulting in higher hardness and improved wear resistance. The grooves in the wear morphology are shallower, and the sizes of spalling and cracks are significantly reduced. The average friction coefficient is reduced by 34.8%, and the wear rate is reduced by 27.5%. The wear mechanism is mainly oxidative wear, accompanied by slight abrasive wear and fatigue wear. This study provides experimental basis and mechanism support for the material design of underwater repair electrodes and the optimization of underwater surfacing repair processes.