In this paper we present a Service Injection and composition Design Pattern for Unstructured Peer-to-Peer networks, which is designed with Aspect-oriented design patterns, and amalgamation of the Strategy, Worker Object, and Check-List Design Patterns used to design the Self-Adaptive Systems. It will apply self reconfiguration planes dynamically without the interruption or intervention of the administrator for handling service failures at the servers. When a client requests for a complex service, Service Composition should be done to fulfil the request. If a service is not available in the memory, it will be injected as Aspectual Feature Module code. We used Service Oriented Architecture (SOA) with Web Services in Java to Implement the composite Design Pattern. As far as we know, there are no studies on composition of design patterns for Peer-to-peer computing domain. The pattern is described using a java-like notation for the classes and interfaces. A simple UML class and Sequence diagrams are depicted.