I can only remember having to deal with one difficult co-worker. She would go around and tell people that my work wasn't up to her standards, and those people she told all would come to me and tell me what she was telling them. I basically just went up to her and told her what I heard, that she was being disrespectful and that I would appreciate her coming to me with issues she has with me because I wasn't trying to lose my job over some bullshyt gossip. It was funny, because the whole time I was talking to her, she was speechless. She's known to talk shyt, but no one had ever confronted her about it until me. From that point forward, she was so nice to me. Basically, whenever you're feeling disrespected, tell them upfront. I feel it's more effective than going over their heads to a supervisor, especially if they are buddy buddy like the two people you work with.