With the BPMN Modeler Plugin you can easily create and edit BPMN models on your Wiki-pages and combine them with everything else you have in Confluence.
Instead of starting from scratch you can also import BPMN 2.0 standard-compliant models. From there on you can make changes to the diagrams directly on your pages. You can export your diagrams as .bpmn or .svg files.
Any saved changes are stored in version increments. No update to your diagram is lost or overwritten.