语言交换伙伴。 http://baike.baidu.com/view/1803244.htm

Thanks Gavin

Most Chinese barely do language exchange stuff, so there is not a wide accepted certain words implies the same meaning. Once we talk about LEP, we usually say:我找了个一起练口语的外国人“meaning"I find a native speaker who can practice speaking with me together." We don't say"语言交流伙伴"，yeah I mean if you say that people can still understand you but it just sounds weird.

语言交流伙伴 It is called "语伴" for short.