Insert Pages is a Wordpress plugin that lets you embed any WordPress content (e.g., pages, posts, custom post types) into other WordPress content using the Shortcode API. It also includes a widget for inserting pages into any widget area. It supports custom post types, whether created programmatically in a theme, or using another plugin like Custom Post Type UI and can abstract away common data types (like videos, quizzes, due dates) into  custom post types, and then show those pieces of content within normal pages and posts by Inserting them as a shortcode.

[insert page='about' display='content']