Strawberry, the receptacle becomes “fruit”. In the so called “seed”, which is the “true fruit”, all parts of (B) Seed are present but the (A) Pericarp is nearly filled by (B) Seed and thus it looks like another “seed skin”. But at microscopic level all layers are still present. Same as Groundnut/Peanut, when the “true fruits” are young the Mesocarp will be fleshy and the “real seed” will be tiny. When the “real seed” grows, it occupies the entire (A) Pericarp and turns it into a hard shell encompassing the seed.
In Cashew Apple/Nut, the pedicel becomes “fruit”. In the “nut”, which is the “true fruit”, (B) Seed parts are present. (A) Pericarp becomes a double shell containing an allergenic gooey irritant.
In Pineapple, the inflorescence (which holds a flower cluster or flower group) and stem become “fruit”. Cultivators won't allow the “real fruits” to mature. If they mature they will become “seed like”, just like Strawberry, and will be placed in pits out side of the “fruit's surface”.
In fact, there are humongous number of species out there in the wild with “seeds” found outside of “fruits”. These are false fruits and are called Accessory Fruits or Pseudocarp. The strange properties of these accessory fruits are, in some cases, unlike Mango or Peach, once cut off from the main plant they won't be getting ripe anymore or the taste won't improve.
Also technically, when we talk about fruits and seeds, it's about flowering plant species, angiosperms, meaning plants that produce seeds within an enclosure (this enclosure is called fruit) as opposed to gymnosperms, meaning “naked” seeds.
So, when the seeds are found outside, they simply become gymnosperms, non-flowering, fruitless, ovary-less species. E.g.: conifers, cycads and ginkgo.