No, this information is not exposed for IAMs. For IAMs, we do keep the file name and path internally, for use by the Update command. The root of each inserted IAM (i.e., first-level node in the tree) shows the name of the file you inserted, but the subassemblies and parts show the occurrence names from the assembly (usually but not always the file name).
DWF files created from IAM files will show the IAM file name at one level further down.
I'm curious as to why you need this. Did you just "forget" where it came from? Or is there a more complex workflow?