I don't think the number of sexual partners either of you have had should be an issue. In a previous relationship the guy I was with had only slept with two people, me included. He felt ashamed of this so initially told me he had slept with around 30 or so women. The truth came out years later and I told him it didn't matter. Because it doesn't.
My husband has slept with quite a few more people than I have, most of them one night stands, he too is ashamed to admit that but I really don't care because he's with me, not them. We all have a past.
But it seems that in your eyes her past isn't exactly 'past', more present because she's still friends with these guys. I can see where you're coming from to a degree, I think many would feel a bit insecure, or at the very least their nose put out of joint because you'll always have it in the back of your mind, is she going to do it again. No one here can tell you if she will or not, because we don't know her. That is totally your call, it is up to you to judge whether or not you think she will do this or if she will remain faithful to you. Hard to tell since you've not been together that long.
If you're really unhappy and it's getting in the way then you have two choices - you can tell her it's them or you and explain how you feel about it, or you can split and move on. Staying with her and her continuing to see these people doesn't sound a realistic option for you because it really sounds as if you have a big problem with that. Which is fine, not everyone would be happy about it. My husband wasn't. When we met I had a couple of friends (who I didn't actually see any more, just chatted occasionally on Facebook) who I'd drunkenly slept with. I had said it would never happen again because I regretted doing it in the first place, I had no interest in them in that way at all. But he said he wasn't happy with me having any contact with them, so out of respect for his feelings and our relationship, I ended those friendships. My husband meant more to me than a couple of people who I rarely spoke to. Some might say he had no right to ask that of me, but he felt uncomfortable and to be honest, I would probably feel the same if the roles were reversed. It's not about insecurity for him, it's the fact I had been intimate with those people, they had seen me naked, I had done stuff with them etc my husband is very protective. He knows he can trust me.
So it's really up to you. Sorry if that's unhelpful, but you can't live a life on the edge of your seat constantly.