If you are worried get Blade Erosion Tape as mentioned above, its not great, but its cheap enough, and (if approved for your Type)
Make sure it's approved for your type!
A few years ago I was with a outfit that had a Hughes 300.The leading edges of the blades showed signs of erosion so the engineer put a NON type approved blade erosion tape on them.
The machine performed normally and the tape seemed to work well. However, a few days later I flew through a rain squall. After I landed the machine I noticed the tape was shattered but I didn't think anything of it as the performance seemed about the same. However, shortly after that I picked up a passenger who asked me to hover about 200 ft. over part of a dense forest. The machine started to lose RRPM. I desperately pumped the collective but it wouldn't stay in the air. Fortunately I was able to put it down in a swamp and suffered no damage - except to my ego. Later on the engineer removed the tape and performance was back to normal. It was a very cheap lesson!