Yep, agree communication is important. A person should feel free to tell their partner of insecurities they mat harbour and should also listen to a partners insecurities without getting pi$$ed off by them.
However, I also think the individuals in the relationship should have some kind of coping mechanism without having to depend on constant talks with a partner to overcome insecurities, some people are particularly insecure and it doesn't matter how much talking and understanding the partner does with them, they will get pi$$ed off by eventually.
Relationship insecurities are the same as any other insecurity, they are there because someone lacks confidence, therefore I believe the best thing a person can do in a relationship is build up their own confidence as an individual, which will lead to less relationship insecurities!