Network coding has been widely recognized as a promising information dissemination approach for wireless networks. However, in practical wireless networks enabled with network coding, different peer sending sequences make significant impact on overall network throughput and transmission delay. In this paper, we study the peer scheduling problem, which is defined as how to intelligently schedule the sending sequence among a group of peers to maximize the wireless coding gain. By conducting an in-depth investigation on the peer scheduling principles in wireless network coding, we propose a cooperative Peer-to-peer Information Exchange (PIE) scheme with an efficient and light-weight peer scheduling algorithm. The PIE scheme can not only fully exploit the broadcast nature of wireless channels, but also utilize the advantage of cooperative peer-to-peer information exchange. Finally, the effectiveness and efficiency of the PIE scheme are demonstrated through qualitative analysis and extensive simulations.