Pages (formerly iWorks Pages) can import and open Microsoft Word documents (.doc, .docx) just fine, so there is nothing more easier than resaving .doc files as .pages file. This is only possible in case that you have access to any of the Apple possible solution, i.e. Mac, or iCloud account for the online version of iWorks.
Without the actual program it will be very hard to reliably produce .pages documents. Some on-line converters claim that they support doc to pages conversion (for example ZAMZAR), but they often save to some previously used format and may not support latest versions.Open DOC file Open PAGES file
Mobile version of popular word processor from Apple
A word processor and layout tool marketed by Apple